vCenter patching failure - Staging interrupted

Products

• VMware vCenter Server

Issue/Introduction

• When attempting to stage updates for the vCenter Server Appliance (VCSA) using a custom offline repository hosted on Internet Information Services (IIS), the staging process fails with UI error Staging interrupted and 
  Check that the URL is valid. If there is no issue with the URL and it is complete, please file a technical support ticket from the support portal.
• The appliance management service logs may indicate an RpmManifestNotFoundException or display file not found errors. Basic HTTP connectivity (wget) may succeed for standard files, but the update payload staging fails.
• /var/log/vmware/applmgmt/applmgmt.log report following errors,
  
  Can't read JSON file /storage/core/software-update/stage/stageDir.json [Errno 2] No such file or directory: '/storage/core/software-update/stage/stageDir.json'
FileNoteFoundError: [Errno 2] No such file or directory: '/mnt/iso-contents/manifest-latest.xml"
• We validated the connectivity to custom repository and using wget we were able to download "manifest-latest.xml"

Environment

vCenter Server Appliance 8.x
vCenter Server Appliance 9.x

Cause

Internet Information Services (IIS) restricts serving files with unknown or unmapped extensions by default, causing the VCSA update staging sequence to fail when attempting to download binary payload files which is not configured in MIME type.

Resolution

Add required extension in MIME type so vCenter can download these files.

• Open the Internet Information Services (IIS) Manager on the server hosting the custom offline repository.  
• Navigate to the specific site or directory level containing the VCSA update repository files.  
• Double-click the MIME Types feature in the main window.  
• Click Add... in the right-hand Actions pane.  
• Enter .* for the File name extension.
  Note: If a wildcard is against security policy, you must explicitly add required repository extensions and map to application/octet-stream
• Enter application/octet-stream in the MIME type field.  
• Click OK to save the new MIME type configuration.  
  Note: For the VCSA staging process, if you do not want to map each specialized extension individually, mapping binary/update payload files (like .rpm, .sign, and .blob) to application/octet-stream is generally the safest approach. This instructs the web server to serve the files directly as raw binary downloads.
• The repository generally relies on the following standard file extensions:
  
  • .blob 
  • .json 
  • .sign
  • . zip
  • .rpm
  • .manifest
  • .SHA256
  • .xml 
• Return to the vCenter Server Appliance Management Interface (VAMI) and retry the URL-based staging process. 

Additional Information

Configure a Custom Repository URL